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R Celiberto - One of the best experts on this subject based on the ideXlab platform.
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calculated low energy electron impact Vibrational excitation cross sections for co2 molecule
arXiv: Chemical Physics, 2016Co-Authors: V Laporta, Jonathan Tennyson, R CelibertoAbstract:Vibrational-excitation cross sections of ground electronic state of carbon dioxide molecule by electron-impact through the CO2-(2\Pi) shape resonance is considered in the separation of the normal Modes approximation. Resonance curves and widths are computed for each Vibrational Mode. The calculations assume decoupling between normal Modes and employ the local complex potential Model for the treatment of the nuclear dynamics, usually adopted for the electron-scattering involving diatomic molecules. Results are presented for excitation up to 10 Vibrational levels in each Mode and comparison with data present in the literature is discussed.
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calculated low energy electron impact Vibrational excitation cross sections for co2 molecule
Plasma Sources Science and Technology, 2016Co-Authors: V Laporta, Jonathan Tennyson, R CelibertoAbstract:Vibrational-excitation cross sections of ground electronic states of a carbon dioxide molecule by electron-impact through CO shape resonance is considered in the separation of the normal Modes approximation. Resonance curves and widths are computed for each Vibrational Mode. The calculations assume a decoupling between normal Modes and employ the local complex potential Model for the treatment of nuclear dynamics, usually adopted for electron-scattering involving diatomic molecules. Results are presented for excitation up to 10 Vibrational levels in each Mode and a comparison with data present in the literature is discussed.
Dvira Segal - One of the best experts on this subject based on the ideXlab platform.
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sharp negative differential resistance from Vibrational Mode softening in molecular junctions
Nano Letters, 2020Co-Authors: Dvira SegalAbstract:We unravel the critical role of Vibrational Mode softening in single-molecule electronic devices at high bias. Our theoretical analysis is carried out with a minimal Model for molecular junctions, ...
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sharp negative differential resistance from Vibrational Mode softening in molecular junctions
Nano Letters, 2020Co-Authors: Junjie Liu, Dvira SegalAbstract:We unravel the critical role of Vibrational Mode softening in single-molecule electronic devices at high bias. Our theoretical analysis is carried out with a minimal Model for molecular junctions, with Mode softening arising due to quadratic electron-vibration couplings, and by developing a mean-field approach. We discover that the negative sign of the quadratic electron-vibration coupling coefficient can realize, at high voltage, a sharp negative differential resistance (NDR) effect with a large peak-to-valley ratio. Calculated current-voltage characteristics, obtained based on physical parameters for a nitro-substituted oligo(phenylene ethynylene) junction, agree very well with the measurements. Our results establish that Vibrational Mode softening is a crucial effect at high voltage, underlying NDR, a substantial diode effect, and the breakdown of current-carrying molecular junctions.
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sharp negative differential resistance from Vibrational Mode softening in molecular junctions
arXiv: Mesoscale and Nanoscale Physics, 2020Co-Authors: Dvira SegalAbstract:We unravel the critical role of Vibrational Mode softening in single-molecule electronic devices at high bias. Our theoretical analysis is carried out with a minimal Model for molecular junctions, with Mode softening arising due to quadratic electron-vibration couplings, and by developing a mean-field approach. We discover that the negative sign of the quadratic electron-vibration coupling coefficient can realize at high voltage a sharp negative differential resistance (NDR) effect with a large peak-to-valley ratio. Calculated current-voltage characteristics, obtained based on ab initio parameters for a nitro-substituted oligo(phenylene ethynylene) junction, agree very well with measurements. Our results establish that Vibrational Mode softening is a crucial effect at high voltage, underlying NDR, a substantial diode effect, and the breakdown of current-carrying molecular junctions.
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path integral simulations with fermionic and bosonic reservoirs transport and dissipation in molecular electronic junctions
Journal of Chemical Physics, 2013Co-Authors: Lena Simine, Dvira SegalAbstract:We expand iterative numerically exact influence functional path-integral tools and present a method capable of following the nonequilibrium time evolution of subsystems coupled to multiple bosonic and fermionic reservoirs simultaneously. Using this method, we study the real-time dynamics of charge transfer and Vibrational Mode excitation in an electron conducting molecular junction. We focus on nonequilibrium Vibrational effects, particularly, the development of Vibrational instability in a current-rectifying junction. Our simulations are performed by assuming large molecular Vibrational anharmonicity (or low temperature). This allows us to truncate the molecular Vibrational Mode to include only a two-state system. Exact numerical results are compared to perturbative Markovian master equation calculations demonstrating an excellent agreement in the weak electron-phonon coupling regime. Significant deviations take place only at strong coupling. Our simulations allow us to quantify the contribution of different transport mechanisms, coherent dynamics, and inelastic transport, in the overall charge current. This is done by studying two Model variants: The first admits inelastic electron transmission only, while the second one allows for both coherent and incoherent pathways.
Anatoly I Ivanov - One of the best experts on this subject based on the ideXlab platform.
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effect of intramolecular high frequency Vibrational Mode excitation on ultrafast photoinduced charge transfer and charge recombination kinetics
Journal of Physical Chemistry B, 2016Co-Authors: Alexey E Nazarov, Vadim Yu Barykov, Anatoly I IvanovAbstract:A Model of photoinduced ultrafast charge separation and ensuing charge recombination into the ground state has been developed. The Model includes explicit description of the formation and evolution of nonequilibrium state of both the intramolecular vibrations and the surrounding medium. An effect of the high-frequency intramolecular Vibrational Mode excitation by a pumping pulse on ultrafast charge separation and charge recombination kinetics has been investigated. Simulations, in accord with experiment, have shown that the effect may be both positive (the Vibrational Mode excitation increases the charge-transfer rate constant) and negative (opposite trend). The effect on charge separation kinetics is predicted to be bigger than that on the charge recombination rate but nevertheless the last is large enough to be observable. The amplitude of both effects falls with decreasing Vibrational relaxation time constant, but the effects are expected to be observable up to the time constants as short as 200 fs. Ph...
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effect of relaxation of intramolecular high frequency Vibrational Mode on nonthermal electron transfer probability stochastic point transition approach
Journal of Physical Chemistry C, 2007Co-Authors: Anatoly I IvanovAbstract:A nonthermal electron transfer assisted by an intramolecular high-frequency Vibrational Mode has been investigated. An analytical expression for the nonthermal transition probability in the framework of the stochastic point-transition approach has been derived. The expression explicitly accounts for the decay of the excited Vibrational states. For the strong electron transfer, the decay of the product state can vastly enhance the nonthermal transition probability in the whole range of parameters except for the areas where the probability is already close to unity. The exploration of electron transfer in the solvent-controlled regime has uncovered that in the solvents exhibiting two or more relaxation time scales the nonthermal transition probability is always larger than that in the solvents with monoexponential relaxation. What is most unexpected is that the appearance of a fast component in the solvent relaxation function with a small weight can considerably increase the nonthermal transition probabilit...
V Laporta - One of the best experts on this subject based on the ideXlab platform.
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calculated low energy electron impact Vibrational excitation cross sections for co2 molecule
arXiv: Chemical Physics, 2016Co-Authors: V Laporta, Jonathan Tennyson, R CelibertoAbstract:Vibrational-excitation cross sections of ground electronic state of carbon dioxide molecule by electron-impact through the CO2-(2\Pi) shape resonance is considered in the separation of the normal Modes approximation. Resonance curves and widths are computed for each Vibrational Mode. The calculations assume decoupling between normal Modes and employ the local complex potential Model for the treatment of the nuclear dynamics, usually adopted for the electron-scattering involving diatomic molecules. Results are presented for excitation up to 10 Vibrational levels in each Mode and comparison with data present in the literature is discussed.
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calculated low energy electron impact Vibrational excitation cross sections for co2 molecule
Plasma Sources Science and Technology, 2016Co-Authors: V Laporta, Jonathan Tennyson, R CelibertoAbstract:Vibrational-excitation cross sections of ground electronic states of a carbon dioxide molecule by electron-impact through CO shape resonance is considered in the separation of the normal Modes approximation. Resonance curves and widths are computed for each Vibrational Mode. The calculations assume a decoupling between normal Modes and employ the local complex potential Model for the treatment of nuclear dynamics, usually adopted for electron-scattering involving diatomic molecules. Results are presented for excitation up to 10 Vibrational levels in each Mode and a comparison with data present in the literature is discussed.
Franco Nori - One of the best experts on this subject based on the ideXlab platform.
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hybrid quantum device with nitrogen vacancy centers in diamond coupled to carbon nanotubes
Physical Review Letters, 2016Co-Authors: Zeliang Xiang, Peter Rabl, Franco NoriAbstract:We show that nitrogen-vacancy (NV) centers in diamond interfaced with a suspended carbon nanotube carrying a dc current can facilitate a spin-nanomechanical hybrid device. We demonstrate that strong magnetomechanical interactions between a single NV spin and the Vibrational Mode of the suspended nanotube can be engineered and dynamically tuned by external control over the system parameters. This spin-nanomechanical setup with strong, intrinsic, and tunable magnetomechanical couplings allows for the construction of hybrid quantum devices with NV centers and carbon-based nanostructures, as well as phonon-mediated quantum information processing with spin qubits.
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energy transfer efficiency in the chromophore network strongly coupled to a Vibrational Mode
Physical Review E, 2015Co-Authors: Franco Nori, Lev G MourokhAbstract:Using methods from condensed matter and statistical physics, we examine the transport of excitons through the photosynthetic complex from a receiving antenna to a reaction center. Writing the equations of motion for the exciton creation-annihilation operators, we are able to describe the exciton dynamics, even in the regime when the reorganization energy is of the order of the intrasystem couplings. We determine the exciton transfer efficiency in the presence of a quenching field and protein environment. While the majority of the protein Vibrational Modes are treated as a heat bath, we address the situation when specific Modes are strongly coupled to excitons and examine the effects of these Modes on the energy transfer efficiency in the steady-state regime. Using the structural parameters of the Fenna-Matthews-Olson complex, we find that, for Vibrational frequencies below 16 meV, the exciton transfer is drastically suppressed. We attribute this effect to the formation of a "mixed exciton-Vibrational Mode" where the exciton is transferred back and forth between the two pigments with the absorption or emission of Vibrational quanta, instead of proceeding to the reaction center. The same effect suppresses the quantum beating at the Vibrational frequency of 25 meV. We also show that the efficiency of the energy transfer can be enhanced when the Vibrational Mode strongly couples to the third pigment only, instead of coupling to the entire system.
